Fast National ratings for Thursday, February 21, 2013.
 
A two-hour "American Idol" installment pushed FOX to the top of the Thursday heap among young viewers, while "The Big Bang Theory" and "Person of Interest" helped keep CBS in first overall.
 
Meanwhile, "The Vampire Diaries" had a big week and helped The CW beat both ABC and NBC in the key demographic for the 8 p.m. hour.
 
Among other notables, it was a dismal week for NBC's "1600 Penn" and, for the first time in a while, ABC's "Scandal" was either flat or down, depending on how the numbers shake out. 
 
On to the ratings...
 
Among adults 18-49, FOX averaged a 3.9 rating for Thursday night, beating the 3.3 rating for CBS in the key demographic. ABC was far back in third with a 2.2 key demo rating, beating NBC's 1.2 rating and the 0.9 key demo rating for The CW.
 
Overall, though, CBS averaged an estimated 13.52 million viewers and an 8.3 rating/13 share for Thursday primetime, nipping the 7.9/12 and 13.5 million viewers for FOX. There was a big drop to ABC's 4.9/8 and 7.16 million viewers and then to the 2.1/3 and 3.17 million viewers for NBC. The CW averaged a 1.4/2 and 2.22 million viewers for the night.
 
[Univision had a big night with 5.84 million viewers and a 2.4 rating among adults 18-49.]
 
8 p.m. - CBS started primetime in first with "The Big Bang Theory" (17.34 million viewers and a 5.4 key demo) and "Two and a Half Men" (13.44 million viewers and a 3.9 key demo). FOX was second for the hour (and first in the 8:30 half-hour) with 13.41 million viewers and a 3.8 rating among adults 18-49, up from the comparable hour last week. ABC's "Zero Hour" averaged 5.32 million viewers and a 1.1 key demo rating, dipping 21 percent in the key demo from last week's premiere. NBC was fourth with "Community" (3.08 million and a 1.1 key demo) and "Parks and Recreation" (3.03 million and a 1.3 key demo). The CW's "The Vampire Diaries" averaged 2.89 million viewers for fifth, but finished third with a 1.3 key demo rating, posting growth in every notable sub-demo.
 
9 p.m. - "Person of Interest" dropped from last week to 14.13 million viewers, but still won the hour, finishing third with a 2.9 rating among adults 18-49. FOX's "American Idol" dominated the key demo with a 4.0 rating and finished a close second overall with 13.6 million viewers. Even with the "Idol" competition, "Grey's Anatomy" was actually up from last week with 8.54 million viewers and a 3.0 key demo rating for ABC. NBC was fourth with a second "Parks and Recreation" episode (2.91 million and a 1.4 key demo rating") and a new "1600 Penn" (2.3 million and a 1.0 key demo). The CW's "Beauty and the Beast" averaged 1.56 million viewers and a 0.6 key demo rating, up from last week.
 
10 p.m. - "Elementary" closed primetime in first overall for CBS with 11.05 million viewers and in second with a 2.3 rating among adults 18-49. ABC's "Scandal" won the hour with a 2.7 key demo rating and finished second with 7.62 million viewers. NBC was third with 3.86 million viewers and a 1.1 key demo rating for a repeat of "Law & Order: Special Victims Unit."
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.